1. Field of the Invention
The present invention relates to a radio-frequency module and a communication device.
2. Description of the Related Art
In the related art, in order to obtain sufficient isolation between input and output sides, the following configuration of a radio-frequency amplifier circuit is known. An input stripline and an output stripline are disposed on different layers of a multilayer substrate between which a ground layer is sandwiched (for example, see Japanese Unexamined Patent Application Publication No. 6-334449).
Nowadays, so-called multiband communication devices that perform communication by selectively using multiple frequency bands (hereinafter simply referred to as “bands”) are available. In such a communication device, a radio-frequency module including plural signal paths for different bands and a switch for selecting one of the plural signal paths is used. In addition to this switch, many circuit elements including a filter element and a matching element for each of the signal paths may be mounted on the radio-frequency module. As the radio-frequency module is being decreased in size and increased in performance, the mounting density of circuit elements is becoming higher. At the same time, the need to secure isolation between an input terminal and an output terminal is also increased.